Correlation Between Macular Structural Changes And Visual Acuity In Patients With Idiopathic Epiretinal Membrane

Objective:This study was based on optical coherence tomography(OCT)and optical coherence tomography angiography(OCTA)to explore the changes of macular structure of idiopathic macular anterior membrane(IERM)and its correlation with visual acuity,and tried to find the structural index of visual prognosis.The differences of macular structure between different groups and the application of OCTA in IERM were also discussed.Methods:Data analysis was based on 53 eyes of 53 different patients.We collected detailed data comprehensively from the patient’s medical history and general physical condition,including the patient’s medical history,age,gender,condition of crystalline lens and history of Ophthalmic diseases.All subjects did comprehensively ophthalmic examination.including slit lamp,naked eye vision,computer optometry,best corrected visual acuity(BCVA),non-contact intraocular pressure,axial length measurement,fundus endoscopy,coherence tomography(OCT)and octa.When proceeding statistics,BCVA was converted to minimum resolution angle logarithm(Log MAR)visual acuity.The foveal retinal thickness(CMT)and foveal choroidal thickness(SFCT)were measured by OCT;The area of foveal vascular zone(FAZ)and vascular density(VD)of retinal superficial vascular complex(SVC)were measured by octa.Control group was consist of eyes from 48 healthy subjects.These were chosen to match the study group’s age and gender.In addition,CMT、FAZ area,VD correlation between BCVA(Log MAR)was analyzed.In terms of IERM phasing,this dissertation divides IERM into four stages,depending on the presence or absence of fovea and ectopic inner fovea layers(Eifls)structure of OCT,which is based on relative study from Govetto et al.Phase 1 is characterized by the presence of macular fovea without distortion of omental structure.Phase 2 is characterized by the absence of macular fovea and thickening of outer nuclear layer.Phase 3 is characterized by clear and continuous inner core layer and inner plexiform layer.Phase 4 is characterized by the disappearance of clear and continuous inner core layer and inner plexiform layer.The different stages of IERM were also divided into three groups:Stage 1 group,stage 2 group and stage 3-4 group.Compare and analyze these IERM groups.Results:There were significant differences in the mean CMT,SFCT,FAZ area and VD of SVC between study group and control group.Compared with control group,the FAZ area of SVC in the eyes in the study group was smaller(χ~2=4.945,P<0.001).The VD of SVC in I study group was larger(χ~2=2.632,P<0.05).CMT increased in study group(t=9.542,P<0.001)and FAZ area was negatively correlated with fovea retinal thickness.The SFCT of the affected eyes in the study group was notably smaller(t=3.598,P<0.001).The FAZ area of SVC was negatively correlated with BCVA(Log MAR)(rs=-0.500,P<0.001);VD was negatively correlated with BCVA(Log MAR)(rs=-0.315,P<0.05);CMT was positively correlated with BCVA(Log MAR)(rs=0.555,P<0.001).In addition,the FAZ area of group1 SVC was smaller(P<0.05)than IERM group 2,and the FAZ area of group 3 was larger(P<0.05)than IERM group 2.CMT in group 2 was thicker than that in group 1(P<0.05);CMT in group 3 was thicker than that in group 2(P<0.05).There was no significant difference in VD(P=0.975)and SFCT(P=0.215)between different groups of IERM.Conclusion:(1)Compared with normal subjects,the macular structure of IERM patients was significantly changed based on OCT.That is,CMT thickens and SFCT decreases.In addition,CMT is negatively correlated with visual acuity,but CMT is not suitable for the assessment of early visual acuity in patients with IERM.(2)Compared with normal subjects,the area of FAZ in SVC layer decreased and VD increased in IERM patients based on OCTA,and both were positively correlated with visual acuity.However,the comparison between IERM groups showed that FAZ area of SVC layer gradually decreased with the increase of stage,while VD showed no significant statistical difference.Therefore,OCTA has no guiding significance for IERM staging at present.(3)The area of FAZ can be used as a morphologic parameter of early vision prognosis in patients with IERM to assist in the evaluation of surgical treatment for IERM.